Pressure responsive apparatus



May 31, 1938. J. w. MCDONNELL 2,118,852

PRESSURE RESPONS IVE APPARATUS Filed March 2, 1956 2 Sheets-Sheet l INVENTOR.

I James 14 fi/Ffla/md/ W W ATTORNEY.

May 31, 1938. J. w. McDONNELL.

v PRESSURE RESPONSIVE APPARATUS 2 Shets-Sheet 2 Filed March 2, 1936 mm mm mm INVENTOR.

ATTORNEY.

James W. MF00/7/7e// w M QQ Q m9 B an Q Q Q Q Q m 5 Q Q Q Q Q r v/ r/ 7 .I 7/ P, .r/ 7/ NM mm QQ mm R mmwm MMQQ Nb QM mm @M WN m-HFm-P Patented May 3l ,,l938 I t l UNITED. STATES PATENT OFFICE Applicatiollll $92, )No. 66,595 r This invention relates generally to apparatus tion with the hose Hi, there is a device ii, which used in conjunction with pneumatic pressure re- I includes a. valve by means of which the flow of ceivers. More specifically, it relatesto apparatus compressed air is controlled. A flexible hose or for-the inflation of the pneumatic tires of motor conduit section [2 leads from device H, and by 5 vehicles, and for indicatingthe amount of tire the use of coupling means 13, connection can be pressures. established to the valve stem ll of a pneumatic It is an object of the invention to provide aptire [5. Certain electrical conductors are shown paratus of the above character, whereby when extending from the device II, to the electrical an air hose is coupled to the tire of an automonet work It.

" tive vehicle, air under pressure will be automati- The construction of the stem I4, and the parts 10 cally supplied to the tire only if the tire pressure 1 carried within the same, can be explained by has dropped below a safe value. reference to Fig. 2. It consists of a tube ll, one It is another object of the invention to provide end of which may connect directly to the inner a novel type of an electrical apparatus for inditube of the tire, and thus take the place of a 15 cating tire pressure, which will function while the standard valve stem, or it may be coupled to a tire is being inflated. valve stem of standard construction, after the Another object of the invention is to provide a valve parts thereof have been removed. Disnovel form of electrical contacting means in conposed withinthe outer tube ii, there is a liner junction with the stem or like part of a pneutube I8, the inner end it! of which is closed. As

2 matic tire, and which is opened and closed in representative of suitable means for retaining 2'0 accordance with variations-in the tire pressure. this liner tube in place; its forward end is shown In this connection the invention is characterized provided with a flange 2|, which is gripped beby the use of magnetic means in conjunction with tween the adjacent end face of tube l1, and the the contacts whereby when the contacts are threaded fitting 22. Disposed within the liner closed, they are held together by amagnetic force tube. It, are the pressure responsive cells 23 5 a which must be overcome before the contacts are and 24.

again opened. Cell 23 consists of a pair of end members 26 A further object of the inventionis to provide and, made of suitable material such as metal, a novel form of pressure sealing valve, which can together with a tube 28 of resilient material, such 30 be used in conjunction with the-stem of a penuas soft vulcanized rubber. Tube 28 has em- 30 'matic tire, and which can be opened without difllbedded in it the convolutions of a helicoidally culty by applying air under pressure. wound wire 29, whereby the tube has sufflcient Additional objects of the invention will apstrength to resist lateral crushing, but can bepear from the following description in which the compressed in the direction of its length, in repreferred embodiment of the invention has been sponse to externally applied pneumatic pressure.

set forth in detail in conjunction with the ac- The ends of wire 29 are shown having electrical companying drawings. v connection with the metal end members 26 and Referring-to the drawings: 21, while the end portions of the rubber tube are Fig. 1 is a schematic view, showing -the manner suitably sealed with respect to the end members pneumatic tire. Pressure cell 24 is of similar construction, in that Fig, 2 is a side elevational'view, in cross-secit incorporates end members 3| and 32. corretio'n, showing parts of myapparatus which can sponding to the end members 26 and 21, a resilbe assembled in conjunction. with atire stem or ient rubber tube 33, and a helicoidal re-enfo'rclike part. ing wire 34. i 45 Fig; 3 is a side elevational view, in-cross-sec- Threaded upon the fitting'22, there is a. coution, showing parts of my apparatus for use in. pling member 36, which is formed to facilitate conjunction with an air hose leading to a source quick attachment to an air hose, as for example bf 8 under l a by providing it with an annular bevelled portion 50. Fig. 4 is a cross sectional detail taken along 31. Connection between coupling member '3 the line 4-4 of Fig. 3. t and threading 22 is sealed by'means of a resil- Refer n fi t t0 8. I have h wn an airient rubber insert 38. To provide for inflow of hose l0, leading from a source of .air under presair during an inflating operation and an autosure, "and such as is used in filling stations for matic check against escape of air, insert ll is the inflation of automotive tires. In c'onjuncformed to provide a check valve. Thus a metal 55 in which my apparatus can be used to inflate a 1Z6 and 21, as by means of a vulcanized bond. 40

terminal 38 is bonded to the insert 36, and is provided with a spherically formed outer surface 4| to which connection can be readily made. Eratending through member 33, and also through the insert 33, there is a passage 42, which is prosressively flattened toward a slit 43 between the resilient rubber lips 44. Slit 43 is normally closed to effect a seal to withhold pressure with- ,in the tube H, but when 'a greater pneumatic pressure is applied to passage 42, the slit is automatically opened. Mounted upon the insert 38 are the spring metal fingers 46, the inner ends.

of which are adapted-to clip into engagement with a stud 41, which projects from the end member 3|. For a purpose to be presently explained, a wire 48 is also embedded in the insert 38, and has its one end connected to terminal member 39, and its other end connected to the metal fingers 46.

An added seal against escape of pneumatic pressure from the interior of tube H, can be provided as followsz-Fitting 22 is provided with an inner annular valve seat 49. This seat is normally engaged by a resilient rubber facing 5|, provided upon the adjacent surface of member 3|. Normally facing 5| engages seat 43, to provide an added seal, in addition to the sealing of silt 43. However, when suflicient pneumatic pressure is applied to passage 42 to open slit 43, facing 6| is forced away a slight amount from seat 43, and such movement is accommodated by the resilient fingers 46.

Insofar as the structure of Fig. 2 has been described, it will be evident that pressure of a tire or receiver to which the tube I! is connected, is distributed about the pressure responsive cells 23 and 24. In this connection n te that free communication is permitted between the space surrounding the liner tube l3, and the interior of this tube, as by means of ports 62. An increase in pneumatic pressure causes both the pressure responsive cells to decrease in length, while a decrease in pneumatic pressure causes these cells to elongate.

Electrical contact means is operated by'expension and contraction of the pressure responslve cells, and can be constructed as follows:- A pair of plungers 53 are provided, which are slidably disposed within the guide tubes 64. These tubes are in turn mounted upon the end members 21- and 32, of the pressure responsive cells 23 and 24. Compression springs '56 normally urge the plungers towards retracted position with respect to the tubes 64. Compression spring 61 however opposes complete retraction of one of the plungers 63. The opposed end faces 53 of the plungers 63, form electrical' contactor surfaces. Fixed within the plungers 63 are the permanent electromagnets 63, which are disposed in such manner as to have unlike poles terminating at the surfaces 66. Thus assuming that the pressure responsive cells 23 and 24 elongate a sufliclent amount, due

to a drop in pressure, to bring the contactingsilrfaces 62 into engagement, the surfaces will be retained together bya definite amount of magnetic attraction. This attraction serves to retain contacting surfacesN-together, until overcome by pull exerted by pressure responsive cells 23 and 24, after pressure in tube I 1 has been increased to a predetermined value. It may be pointed out at this time that the relationship between the parts is such that contacting surfaces 68 do not come into engagement until the tire pressure, and the pressure within tube I 1, falls below a safe operating value. Upon increasing the pressure by inflating the tire, it is evident from the above that the pressure must be increased a considerable degree, to cause the contacts 58 to break, which pressure may correspond generally to a proper operating pressure, or a pressure to which it is desirable to inflate the tire.

With respect to the electrical connections made to the contactor surfaces 58, it should be noted that these surfacesare in electrical contact with the guide tubes 54, which in turn connect to the embedded wires 29 and 34, of the pressure responsive cells. The other end of wire 23 con- .nects through end member 26 to the tube II, which in turn is grounded to the external casing or tube ll. Wire 34 connects through member iii, to the spring fingers 46, and from thence through wire 48 to the connector member 33. Thus electrical connection to the contactor surfaces 58, can be established by making electrical connection with the metal coupler part 36, and to the terminal member 39.

In addition to the electrical contacts or contactor surfaces 58, it is desirable to provide electrical means making it possible to measure or secure an index of the pneumatic pressure within the tire. For this purpose tubular magnetic cores 6| and 62, are shown mounted upon the end member 3|, and similar cores are mounted upon the end member 26 for the pressure cell 23. These tubular cores are adapted to interleave with similarly formed plates 63 and 64, carried by the end members 21 and 32. The magnetic cores associated with each of the pressure responsive cells form variable magnetic flux paths, which assist in varying the inductive reactance of the helicoidally wound wires 29 and 34 as the cells expand or contract.

In addition to the variable magnetic means formed as described above, a variable condenser is arranged between the pressure responsive cells, and -is-electrically connected in shunt with the contactor surfaces 53. Thus tubular condenser plates 66 and 61 are carried by the end member 21 of cell 23, and are arranged to interleave with tubular condenser plate 68, carried by the end member 32. A sleeve 69 of insulating material can be interposed between the tubular plate 66 and the guide tubes 54, in order to avoid short circuiting. Likewise a guide sleeve H of insulating material, can be interposed between the outer tubular condenser plate 61, and the adjacent inner surface of the liner tube l3. With such an arrangement it is evident that when the contactor surfaces 56 are moved apart, the variable electrical condenser formed by the tubular plates 66 and 61, in conjunction with tubular plate 66, is decreased in value. I

The device H, previously referred to in connection with Fig. 1, is illustrated ,in detail in Figs. 3 and 4. According to the details illustrated it consists ofa relatively rigid section 12, formed of suitable material such as a molded condensate product, which has a passage 13 extending through the same. In order to form an electrically operated valve, 9. plunger 14 of mag netic material is slidably mounted in the passage 13. One end of this plunger carries a ball 16, adapted to seal upon a valve seat TI. A compression spring 18 serves to urge the plunger 14 in a direction to close ball 16 upon the seat 11.

The plunger can be provided with longitudinal grooves 19, to permit flow of air past the same. Surrounding the passage 13 there is a magnetic winding 3|, which is connected to the two 0011- ductors l2 and ll of an electric cord ll. One end of section 12 is provided with a suitable fltting ll,

' for coupling the same to the air hose II. Section through valve seat 11.

12 carries an extension l1, which contains a central metal tube ll, the passagethrough this tube being in communication with the e 1l Extension l1 is coupled'to the flexible conduit II, which is shown provided with both inner and outer flexible metal sheaths ll and ll. As illustrated, the inner flexible sheath ll is electrically connected with one end of the metal tube ll, while the outer metal sheath II is electrically connected to a metal sleeve ll, surrounding extension l1. Tube ll is also electrically connected with a metal sleeve ll, which surrounds the main body of section 12.

A simple form of switch 94 is shown mounted in a position convenient to be manipulated by the hand of an operator. This switch is shownconsisting of a movable contact ll, carried by the spring strip 91, and cooperating with a stationary contact ll. Gontact 06 connects with sleeve ll, and thence, through tube ll, to the inner'flexible sheath ll. Stationary contact ll is electrically P connected to sleeve 92, and to the outer flexible metal sheath ll. By manually depressing the push-button 99, the contacts ll and ll, are closed. The contacts" of this switch also connect with conductors Ill and I02, of a flexible electrical cord IIIl.

A part of suitable coupling means, for making quick coupling engagement with the device I4, is also illustrated in Fig. 3. It consists of a pair of levers Ill, pivotally carried by a sleeve Ill which is secured to the end of the flexible conduits I2. These levers carry finger engaging arms I01, and can bepressed inwardly by the operator against the springs Ill. Levers Ill also carry' arcuate bevelled portions Ill, which are adapted to engage over the'annuiar bevelled portion ll of the coupling part ll (Fig. 2). In establishing such connection it is evident that the outer flexible metal sheath ll of the conduit is electrically connected,.through levers Ill and arcuate portions Ill, with the coupling part ll and the tube I1. Likewise the terminal member ll of the device shown in Fig. 2, is pressed into electrical engagement with the exposed end of the inner metal sheath Il Thus electrical connections are automatically established between the device of Fig. 2, and the electrical contacts ll and Ill The electrical network ll, illustrated in Fig. 1, can be formed as iollows:-An electron type of rectifier tube III is provided, .which is provided with the anodes or plates II2. A power supply transformer II! has one secondary winding IIl, with its terminals connected to the plates III. Another secondary winding II1 can be provided for heating the cathode Ill. Conductor lla which is connected to conductor ll of cord ll, leads to center tap on the secondary winding II1. Conductor lla, which is connected to conductor ll of cord ll, leads to one side of a choke inductance Ill, the other side of which connects with a third secondary transformer winding Ill.

- The other terminal of winding III is connected nected through condenser III to a'point between choke Ill and winding I2I.

Operation of my complete apparatus can now be outlined as follows-Assuming that the inflation stem of a pneumatic tire is equipped as described with respect to Fig. 2, when the pressure of the tire falls below a safe value, elon8ation of the pressure responsive cells ll and 24, brings the contactor surfaces ll into engagement. If now engagement is made with respect to the coupling means Il, a circuit is established with respect to conductors Illa and Illa, by means of which these conductors are shunted by the closed contactors ll. Thus direct current from the rectifier is caused to flow through the winding lI, because leads lla and lla are now connected across the center taps on windings Ill and H1, in series with choke Ill and winding IZI. Rectifled current flow in winding lI, retracts the magnetic plunger", and opens the ball 1l with respect to valve seat 11. Compressed air immediately flows from hose ll, through the valve seat 11 and the flexible conduit I2, and into the valve stem past the normally closed slit ll and the secondary valve seat 4!. After the tire has been inflated to a value approximating that de-' sired, pressure responsive cells 2l and ll exert suflicient force to overcome the magnetic attraction between the permanent electro-magnets SI, and therefore the contactor surfaces II are pulled apart. This immediately opens the rectifler circult, with the result that rectified current ceases to flow through the winding II, and ball 16 closes upon its seat.

Assuming that connected to the transformer Ill is of suitable frequency, some alternating current continues to 1 actance values of the inductive pressure cell windings vary with changes in pressure, and since? pressure variations likewise vary the capacitance formed by plates 66, 61 and ll, the alternating current flow will vary in accordance with the tire pressure and the meter I22 can be calibrated to read in terms of pressure per square inch.

If after the tire has been inflated to a pressure sumcient to cause the contactor surfaces ll to open, it is desired to further increase the tire pressure, switch button ll is depressed, to place a temporary short circuit across the conductors IlIa and Illa, and thus cause rectified current to flow in winding ll to open the ball 16.

In the event it is not desired to employ anelectric meter in the manner described, for the purpose of indicating the pressure 013- a tire, it is evident that this meter can be omitted. Likewise in such event the variable reactance elements incorporated in the tire stem, can be omitvted.

It is evident that my apparatus can be used to advantage by gasoline fllling stations, where considerable time is now wasted in alternately inflating and pressure readings of tires. with my apparatus it is only necessary for the operator to establish coupling with the tire stem, to automatically inflate the tire to a predetermined degree, after which there is an automatic pressure reading. It the pressure of the tire is not below a safe value, then no air will beintroduced if the operator attempts an inflating operation. If however, the operator desires to introduce additional air, this can be accomplished by depressing the button ll.

the alternating current supply I claim:

1. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with a pressure receiver, a pair of electrical contacts carried within said tube, pressure responsive means likewise carried within said tube and serving to efiect opening and closing of said contacts in accordance with pressure of gas within the receiver, a hose adapted to be connected to a source of gas under pressure, coupling means for making quick detachable connection between one end of said hose and the other end of said tube, said last means including metal parts forming two electrical conductors insulated with respect to each other, and electrically connected to said electrical contacts.

2. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with a pressure receiver, a pressure responsive cell disposed within said tube, an electrical contact carried by one end of said cell, another electrical contact associated with said first named contact, magnetic elements associated with both said contacts and serving to exert a force tending to retain said contacts closed until said contacts are pulled apart with sufllcient force to overcome said magnetic attraction.

3. In apparatus of the character described for use with pressure receivers, a tube having one end oi the same communicating with a pressure receiver, a pressure responsive cell disposed within said tube, said cell including end walls con nected by resilient side walls, whereby'when external pressure upon the same is increased, said end walls are forced towards each other, mounting means for said cell serving to fix one end wall of the same with respect to the tube, an electrical contact carried by the other end wall "of said cell, a second electrical contact carried within said tube and cooperating with said first named contact, and magnetic means associated with both.said contacts, and providing a predetermined magnetic force tending to retain the same in closed condition.

4. In apparatus of the character described, a tube having one end of the same adapted to communicate with a pressure receiver, a pressure responsive cell disposed within said tube, said cell being formed of end wallsand tubular side walls of resilient material connecting the end walls, said side walls having a helicoidally formed wire embedded therein, and interleaved plates of an electrical condenser carried by said end walls and electrically connected to the terminals of said wire.

5'. In apparatus of the character described, a tube having one end of the same adapted to communicate with a pressure receiver, a pair of pressure responsive cells disposed within said tube, each of said cells being adapted to contract in the direction of the axis of the tube when the pressure within the receiver increases, interleaved plates of a variable electrical condenser associated with each of said cells, and interleaved plates of a variable condenser interposed between said cells.

6. In apparatus of the character described, a tube having one end of the same adapted to communicate with a pneumatic pressure receiver, a

pair of pressure responsive cells disposed within said tube, each of said cells including a pair of endrnembers connected by tubular side walls of resilient material. said side walls being reinforced by a helicoidally wound wire embedded in the same, whereby each cell is adapted to expand and. contract responsive to varying pressures within said receiver, in a direction longitudinally of the axis of the tube, interleaved plates of a variable electrical condenser disposed within each of said pressure responsive cells, each of said condensers being electrically connected to the terminals of thehelicoidally wound wire for the associated wlls, means serving to retain said cells in substantial alignment, with their respective remote end members substantially fixed with respect to the tube, and interleaved plates of a variable electrical condenser carried by the adjacent end members of said cells, whereby when said cells are caused to expand and contract responsive to varying pneumatic pressure within said receiver, the reactance values of all of said variable electrical condensers are varied.

7. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with a pressure receiver, a hose adapted to be connected to a source of gas under pressure, coupling means for detachably connecting one end of the hose to the other end of the tube, an electrically operated valve serving to control flow of gas through said hose, and means responsive to pressure within the receiver for effecting opening and closing of said valve, said last means including an electrical energizing circuit having at least one conductor of the same established through said coupling means, whereby said circuit is disrupted when said hose is disconnected with respect to said tube.

8. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with a pressure receiver, a hose adapted to be connected to a source of gas under pressure, coupling means for detachably connecting one end of the hose'to said tube, a valve associated with the hose and serving to control flow of gas through the same, and means responsive to pressure within the receiver for efiectlng opening and closing of said valve, said last means including a pair of electrical contacts disposed within said tube, and means likewise disposed within said tube responsive to the pressure of gas within the receiver for effecting opening and closing movements of said electrical contacts. I

9. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with the pressure receivcr, a hose adapted to beconnected to a source of gas under pressure, coupling means for detachably connecting one end of the hose to said tube, a pair of electrical contacts carried within said tube, means incorporated in said coupling means for making electrical connection with said contacts, means responsive to pressure within the receiver for elfecting opening and closing of said contacts, valve means for controlling flow of gas through said hose, and means controlled by closing and opening of said contacts for controlling opening and closing of said valve.

10. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with the pressure receiver, a hose adapted to be connected to a source of gas under pressure, coupling means for detachably connecting one end of the hose to the other end of said tube, whereby said hose can be quickly attached or disconnected with respect to said tube,- an electrically operated valve associated with said hose and serving to control flow of gas through the same, and means responsive to pressure within the receiver for eflecting energlzation of said valve, said last means including a pair of electrical contacts carried within said tube, pressure responsive means likewise carried within said tube and adapted to move said contacts between open and closed positions, and current carrying conductors extending from said contacts and formed in part by said coupling means, whereby when said hose is detached with respect to said tube electrical connection with said contacts is disrupted.

11. In apparatus of the character described for use with pressure receivers, a tube having one end of the same communicating with a pressure receiver, a pair of electrical contacts carried within the pressure within the receiver exceeds a pre- 10 determined value.

JAMES W. McDONNELL. 

